Embolic protection system

ABSTRACT

An embolic protection system  1  comprises a guidewire  99  for advancing through a vasculature, the guidewire  99  having a distal end and a proximal end; an embolic protection filter  1  having a filter body  41  with a distal end and a proximal end, the filter body  41  providing for a collapsed configuration and an expanded deployed configuration. The embolic protection filter body  41  has a guidewire path for slidably receiving the guidewire  99  to permit movement of the filter  1  relative to the guidewire  99  when the filter  1  is in the collapsed configuration and the expanded deployed configuration. A delivery catheter  2  is advanceable over the guidewire  99  for delivery of the embolic protection filter  1 ; the delivery catheter  2  having a proximal end and a distal end. The filter  1  is deployed from the distal end of the delivery catheter  2  into the expanded deployed configuration. A retrieval catheter  3  is also advancable over the guidewire  99  for retrieval of the filter  1 , the retrieval catheter  3  having a distal end and a proximal end; and engagement elements for engaging the embolic protection filter  1  with the guidewire  99  for retrieval of the filter  1  into the retrieval catheter  3  in the collapsed configuration.

This invention relates to a transvascular embolic protection system forsafely capturing and retaining embolic material released during aninterventional procedure while maintaining blood flow.

WO-A-99/23976 describes various embolic protection systems of this type.WO-A-99/51167 and WO-A-99/51166 describe delivery catheters for deliveryof an embolic protection filter to a desired site in the vascularsystem. Various embolic filters are described in WO-A-00/67668),WO-A-00/67669 WO-A-00/67670 and WO-A-00/67671. A retrieval catheter foruse with such embolic protection systems is described in WO-A-01/12082.

There is an economical and clinical need to provide an improved embolicprotection system which will be easy and convenient for a clinician toprepare for use, to deploy and to retrieve. In addition there is a needto provide such a system which will facilitate a wide range of clinicalprocedures to be carried out.

STATEMENTS OF INVENTION

According to the invention there is provided an embolic protectionsystem comprising:—

-   -   a guidewire for advancing through a vasculature, the guidewire        having a distal end and a proximal end;    -   an embolic protection filter having a filter body with a distal        end and a proximal end, the filter body providing for a        collapsed configuration and an expanded deployed configuration;    -   the embolic protection filter body having a guidewire path for        slidably receiving the guidewire to permit movement of the        filter relative to the guidewire when the filter is in the        collapsed configuration and the expanded deployed configuration;    -   a delivery catheter advanceable over the guidewire for delivery        of the embolic protection filter; the delivery catheter having a        proximal end and a distal end, the filter being deployed from        the distal end of the delivery catheter into the expanded        deployed configuration;    -   a retrieval catheter advancable over the guidewire for retrieval        of the filter, the retrieval catheter having a distal end and a        proximal end; and    -   engagement elements for engaging the embolic protection filter        with the guidewire for retrieval of the filter into the        retrieval catheter in the collapsed configuration.

In one embodiment of the invention the guidewire path is in isolationfrom the embolic material captured within the filter body.

In a preferred case the tubular guidewire path is defined by a tubularsleeve. Ideally the tubular sleeve extends from the proximal end to thedistal end of the filter. Desirably the guidewire path is a tubularguidewire path.

In another embodiment the engagement elements comprise a guidewireengagement element on the guidewire and a filter engagement element onthe filter, the engagement elements co-operating to provide selectiveengagement and positioning of the filter with respect to the guidewire.Preferably the engagement element of the guidewire comprises a guidewireabutment on the guidewire.

The guidewire abutment may be located at the distal end of theguidewire.

The guidewire abutment may be located proximal of the distal and of theguidewire.

In a particularly preferred embodiment the engagement element of thefilter comprises a filter abutment on the filter.

The filter abutment may be a distal abutment on the filter.

The filter abutment may be a proximal abutment on the filter.

Most preferably the tubular guidewire path is defined by a sleeve andthe filter abutment is provided by the sleeve.

In another embodiment of the invention the engagement elements comprisereleasable locking elements. Preferably the releasable locking elementscomprise a taper lock. Ideally the guidewire engagement elementcomprises a locking ring on the guidewire and the filter engagementelement comprises a tapered surface of the filter, the locking ringhaving a tapered surface which is engageable with the tapered surface ofthe filter to lock the filter to the guidewire. Most preferably thelocking ring is a split ring.

In another case the embolic protection system includes a tube advancableover the guidewire, the locking ring being located between a distal endof the tube and the filter for retrieval of the filter.

Desirably the releasable locking means includes a tether engageable withthe filter for retrieving the filter into the retrieval catheter.

In a preferred embodiment the embolic protection system comprisesdeployment means for moving the collapsed filter relative to the distalend of the delivery catheter. Preferably the deployment means comprisesa tube which is advancable over the guidewire for engagement with theproximal end of the filter, the tube being movable longitudinallyrelative to the delivery catheter for deployment of the filter from thedistal end of the delivery catheter.

In another embodiment the embolic protection system includes loadingmeans for loading the filter into the delivery catheter. Ideally theloading means comprises a funnel having a narrowed portion disposed atthe distal end of the delivery catheter and an enlarged portion forreceiving a proximal portion of the filter in the expandedconfiguration, the filter being progressively collapsed as it is movedthrough the funnel for loading into the delivery catheter.

In a further embodiment the embolic protection system includesengagement means for engaging the filter within the retrieval catheter.Preferably the engagement means comprises a frictional engagementbetween the filter body and an internal surface of the distal end of theretrieval catheter. Most preferably the engagement means comprisesprojections on the inner surface of the retrieval catheter adjacent thedistal end thereof.

In another preferred embodiment the delivery catheter includes anelongate slot disposed in a first sidewall thereof at a first distallocation which is spaced a relatively longer distance from the proximalend of the delivery catheter than from the distal end of the deliverycatheter, and wherein the inner deployment catheter includes an aperturedisposed in a second sidewall thereof at a second distal location whichsubstantially corresponds with said first distal location for saidelongate slot, thereby permitting co-operative movement of said filterwith respect to said guidewire and associated delivery and deploymentcatheters for selective deployment of the filter while facilitating therapid exchange of said catheter and filter assembly over a guidewirewithout the utilisation of exchange wires or extension wires.

The embolic protection filter may comprise a collapsible filter body,the proximal inlet end of the filter body having one or more inletopenings sized to allow blood and embolic material enter the filterbody, the distal outlet end of the filter body having a plurality ofoutlet openings sized to allow through passage of blood but to retainundesired embolic material within the filter body. Ideally the filtercomprises a collapsible filter support frame having a proximal end and adistal end, the filter support frame being movable between a collapsedposition for movement during delivery through the vascular system and anextended outwardly projecting position to support the filter body in anexpanded position thereby urging the filter body into apposition withthe vasculature upon deployment. Most preferably the embolic protectionsystem comprises a guide olive provided at the distal end of the filterbody.

Desirably the embolic protection system comprises an inner elongatesleeve to which the filter body and the filter support frame aremounted, the sleeve having a proximal end and a distal end, the guideolive extending distally of the sleeve distal end.

the proximal end of the filter support frame and the inlet end of thefilter body are preferably attached to the proximal end of the sleeve.

The guide olive may be integral with the filter body.

Ideally the guide olive tapers distally inwardly.

In another aspect the invention provides a method for the capture andremoval of embolic material from a blood vessel during an interventionalprocedure comprising the steps of:—advancing a guidewire through avasculature;

-   -   crossing a desired treatment location with the guidewire;    -   introducing over the guidewire a collapsible embolic protection        filter having a collapsed configuration, the collapsed        configuration permitting delivery and withdrawal of the filter;    -   deploying the filter distal to the treatment location;    -   carrying out the interventional procedure, embolic material        generated during the treatment procedure being captured by the        deployed filter;    -   advancing a retrieval catheter over the guidewire;    -   collapsing the filter into the retrieval catheter and with it        the captured embolic material;    -   withdrawing the retrieval catheter and the collapsed filter from        the vasculature leaving the guidewire in the vasculature.

In one embodiment of the invention the method comprises the step ofproviding a catheter over the guidewire after withdrawal of theretrieval catheter.

In another embodiment the method includes the step of moving theguidewire after withdrawal of the retrieval catheter and the collapsedfilter from the vasculature to re-position the guidewire in thevasculature.

The catheter may be a catheter for delivery of a diagnostic medium.

The catheter may be a catheter for delivery of a lytic agent.

The filter is preferably slidably disposed on the guidewire when thefilter is in the expanded deployed configuration.

In one preferred case the filter is rotatably disposed on the guidewirewhen the filter is in the expanded deployed configuration.

In a further embodiment the method includes the steps of:—

-   -   loading the filter in a collapsed configuration within a        delivery catheter;    -   advancing the delivery catheter and filter over the guidewire to        deliver the filter to a desired location; and    -   deploying the filter from the delivery catheter at the desired        location.

Preferably the method includes the steps of:—

-   -   collapsing the filter from an expanded configuration for loading        the filter into the delivery catheter;    -   the filter being expanded to a deployment configuration on        release from the delivery catheter.

The treatment location may be a region of stenosis.

In one embodiment the interventional procedure includes a balloondilation of the stenosis while the filter is deployed.

In another embodiment the interventional procedure includes a stentingof the treatment location while the filter is deployed.

According to another aspect of the invention there is provided a medicalcatheter for transvascular delivery and deployment of an embolicprotection filter, the catheter comprising:—

-   -   an outer catheter tube defining a distal end; and    -   an inner catheter tube defining a distal end;    -   the outer tube being at least partially movable relative to the        inner tube between a delivery configuration in which the distal        end of the outer tube extends distally of the distal end of the        inner tube to define a reception space for an embolic protection        filter within the outer tube, and a deployment configuration in        which the distal end of the inner tube extends distally of the        distal end of the outer tube for deployment of the embolic        protection filter;    -   the inner catheter tube providing compressive resistance and the        outer catheter tube providing stretch resistance.

In one embodiment the inner catheter tube at least partially comprises arelatively stiff core encased in a more pliable body.

In another embodiment the outer catheter tube at least partiallycomprises a relatively stiff core encased in a more pliable body.

The core is preferably oriented to prevent elongation of the outercatheter tube and/or compression of the inner catheter tube.

The core may comprise a mesh.

In one case the core comprises a plurality of longitudinally orientedstrips of a stiff material. In another case the core comprises aplurality of circumferentially oriented strips of a stiff material.

The core may be of a metallic material. The metal is preferablystainless steel.

The pliable body may be of a plastics material. The plastic ispreferably polyamide.

In a further aspect the invention provides an embolic protection devicecomprising:

-   -   a collapsible filter element for delivery through a vascular        system of a patient;    -   the filter element comprising a collapsible filter body and a        collapsible filter support frame contacting the filter body;    -   the filter body having an inlet end and an outlet end, the inlet        end of the filter body having one or more inlet openings sized        to allow blood and embolic material enter the filter body, the        outlet end of the filter body having a plurality of outlet        openings sized to allow through passage of blood but to retain        undesired embolic material within the filter body;    -   the filter support frame being movable between a collapsed        position for movement through the vascular system and an        extended outwardly projecting position to support the filter        body in an expanded position;    -   the frame having an intermediate section to urge the filter body        in the expanded position into apposition with a vessel wall, and        a proximal section extending radially inwardly of the        intermediate section;    -   at least part of the proximal section of the frame being spaced        distally to accommodate inflow of embolic material through the        inlet openings in the expanded position.

In one embodiment of the invention the filter body comprises one or morelinking webs between adjacent inlet openings, and a part of the proximalsection of the frame extends radially inwardly in alignment with thewebs.

The frame proximal section preferably comprises one or more frameelements, at least one frame element providing the part of the proximalsection spaced distally. Ideally at least one frame element provides thepart of the proximal section extending radially inwardly in alignmentwith a linking web between adjacent inlet openings. Most preferably thenumber of frame elements is four, two frame elements extending radiallyinwardly in alignment with two webs between two inlet openings, and twoframe elements spaced distally of the inlet openings.

Desirably the support frame is gold-plated and electropolished.

According to the invention there is also provided an assembly forloading a collapsible embolic protection filter into a catheter, theassembly comprising:—

-   -   a catheter defining a reception space at a distal end of the        catheter for receiving a collapsed embolic protection filter;    -   a separate removable pushing device for delivering the medical        device into the reception space.

In one embodiment the assembly comprises a separate loading device tocollapse the embolic protection filter, the loading device defining aninlet end and an outlet end, the outlet end being configured forco-operative alignment with the reception space.

The pushing device may comprises a proximal stop for engagement with theembolic protection filter. Preferably the pushing device comprises astem, the stem having a distal stop for engaging the embolic protectionfilter. Ideally the pushing device comprises a handle.

In another embodiment the loading device comprises means for radiallycompressing the embolic protection filter.

the loading device preferably comprises a funnel, the inlet end defininga larger cross sectional area than the outlet end. Ideally the loadingdevice comprises a main support having a funnel-shaped bore formed froma frusto-conical embolic protection filter receiving portion terminatingin a cylindrical portion formed by a loading tube projecting from themain support for alignment with the reception space before loading.

The cone angle of the funnel is preferably between 15° and 65°. Mostpreferably the cone angle is between 35° and 45°.

In a preferred embodiment of the invention the loading device extendsinto the reception space.

In another preferred embodiment of the invention the loading deviceextends around the outside of the reception space.

In a further embodiment the assembly comprises a tray, the traycomprising a first retaining means for releasably supporting the pushingdevice in a disengaged position before delivering the embolic protectionfilter into the catheter. Preferably the assembly comprises a secondretaining means for releasably supporting the loading device inco-operative alignment with the catheter during loading.

The retaining means may comprises a channel for receiving the loadingdevice and/or the catheter and/or the pushing device, and at least oneprojection on the channel wall projecting inwardly for snap retention ofthe loading device and/or the catheter and/or the pushing device.

Ideally the tray comprises a liquid retaining bath formed by a recess inthe tray, the bath having a depth sufficient to accommodate in a totallysubmerged state the reception space of the catheter and the embolicprotection device for submerged loading of the embolic protection filterinto the reception space.

The tray preferably has a catheter holding channel communicating withthe bath, the channel defining a pathway around the tray which supportsthe catheter in a loading position on the tray.

In another embodiment means for securing the catheter within the channelcomprises a number of retainers spaced-apart along the channel, eachretainer comprising two or more associated projections which projectinwardly from opposite side walls of the channel adjacent a mouth of thechannel, the projections being resiliently deformable for snapengagement of the catheter within the channel behind the projections.

A ramp may be provided at an end of the channel communicating with thebath to direct the reception space of the catheter towards a bottom ofthe bath.

Ideally means is provided within the bath for supporting the receptionspace of the catheter above the bottom of the bath.

Said supporting means is preferably a step adjacent the channel.

The first retaining means may be provided within the bath.

Desirably the assembly comprises a flushing means. Most preferably theflushing means comprises a syringe.

In a further aspect of the invention there is provided a method ofloading an embolic protection filter into a catheter, the methodcomprising the steps of:—

-   -   providing an embolic protection filter, the embolic protection        device being collapsible;    -   providing a embolic protection catheter defining a reception        space at a distal end of the catheter for receiving the        collapsed embolic protection filter;    -   providing a pushing device for delivering the embolic protection        filter into the reception space;    -   delivering the embolic protection filter into the reception        space using the pushing device; and    -   removing the pushing device from the reception space.

In one embodiment the method comprises the steps of:

-   -   providing a loading device to collapse the embolic protection        filter, the loading device defining an inlet end and an outlet        end;    -   aligning the outlet end of the loading device in co-operation        with the reception space; and    -   delivering the embolic protection filter through the inlet end        of the loading device and into the reception space.

In a preferred case the catheter comprises an internal proximal stop,and the method comprises the step of moving the collapsed embolicprotection filter proximally in the reception space using the pushingdevice to engage the internal proximal stop and disassociate the loadedcatheter from the loading device before removing the pushing device.

The catheter may be constrained relative to the loading device beforedelivery of the embolic protection filter through the loading deviceinto the reception space, and the method comprises the step of releasingthe constraint to facilitate disassociation of the loaded catheter fromthe loading device.

In another embodiment the pushing device comprises a wire for threadingthrough the embolic protection filter, the wire defining a distal stopfor engaging the embolic protection filter.

The loading device may comprise an elongate neck at the outlet end, andthe method comprises the step of at least partially positioning theelongate neck in the reception space before delivering the embolicprotection filter into the reception space.

In a preferred embodiment the method comprises the step of flushing theembolic protection filter before delivering the embolic protectionfilter into the reception space.

Ideally the method comprises the step of flushing the catheter beforedelivering the embolic protection filter into the reception space.

In a preferred case the catheter comprises an outer catheter tube and aninner catheter tube, the inner catheter tube defining the internalproximal stop.

Desirably both the inner catheter tube and the outer catheter tube areflushed before delivering the embolic protection filter through theloading device.

In another aspect the invention provides a method of loading an embolicprotection filter into a catheter, the method comprising the steps of:—

-   -   providing a embolic protection filter, the embolic protection        filter being collapsible;    -   providing a catheter defining a reception space at a distal end        of the catheter for receiving the collapsed embolic protection        filter, the catheter comprising at least one internal proximal        stop;    -   providing a loading device to collapse the embolic protection        filter, the loading device defining an inlet end and an outlet        end;    -   aligning the outlet end of the loading device with the reception        space;    -   delivering the embolic protection filter through the loading        device and into the reception space; and    -   moving the collapsed embolic protection filter towards its        proximal end in the reception space to engage said at least one        the internal proximal stop and disassociate the loaded catheter        from the loading device.

In one embodiment the method comprises the steps of:—

-   -   providing a pushing device for delivering the embolic protection        filter through the loading device and into the reception space,        and for engaging the collapsed embolic protection filter with        the internal proximal stop; and    -   removing the pushing device after disassociating the loaded        catheter from the loading device.

In a preferred embodiment the pushing device comprises a wire forthreading through the embolic protection filter, the wire defining adistal stop for engaging the embolic protection filter.

The loading device preferably comprises an elongate neck at the outletend, and the method preferably comprises the step of at least partiallyaligning the elongate neck with the reception space before deliveringthe embolic protection filter through the loading device.

The method may comprise the step of flushing the embolic protectionfilter before delivering the embolic protection filter through theloading device.

The method may comprise the step of flushing the catheter beforedelivering the embolic protection filter into the reception space.

In a preferred embodiment the catheter comprises an outer catheter tubeand an inner catheter tube, the inner catheter tube defining theinternal proximal stop.

Desirably both the inner catheter tube and the outer catheter tube areflushed before delivering the embolic protection filter through theloading device.

According to a further aspect of the invention there is provided aremovable device for loading a collapsible embolic protection filterinto a catheter, the device comprising a distal stop for releasablyengaging with the embolic protection filter to push the embolicprotection filter towards a proximal end of a catheter thereby loadingthe embolic protection filter into the catheter.

The distal stop is preferably provided on an elongate stem.

Most preferably the distal stop is integral with the stem.

In one case the distal stop comprises a step in the stem from a smalldiameter portion proximal of the step to a large diameter portion distalof the step.

The small diameter portion preferably has a diameter of approximately0.014″ (0.3556 mm).

The large diameter portion preferably has a diameter of approximately0.018″ (0.4572 mm).

The distal stop may be attached to the stem.

Ideally the stem comprises a wire.

The stem may comprise a low friction coating for ease of threadingthrough the medical device. Ideally the coating is ofpolytetrafluoroethylene.

In one case the device comprises a handle.

The invention provides a clinician with the freedom to select fromdifferent guidewires prior to selection of an embolic filter.

Prior art assemblies suffer from the disadvantage that differentguidewires cannot be used with a particular filter during aninterventional procedure. A clinician is thus constrained to discardboth the guidewire and the filter if the guidewire proves unsuitable,for example because it is too stiff or some other mechanical property isundesirable.

An important advantage of the invention is that because the filter isnot attached to the guidewire in a collapsed configuration for delivery,the guidewire which is first advanced through the vasculature has alower profile. Therefore the guidewire alone can more easily navigatenarrow and tortuous regions of the vasculature.

Another important advantage of the invention is that because the filteris not fixed to the guidewire, if the deployed filter is mis-sized withrespect to the region of the treatment site it is free to be carrieddistally by blood flow to a narrow section of the vasculature at whichthe filter effectively achieves apposition with the vessel wall. Thisensures that all blood flow with entrained embolic material passesthrough the filter.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more clearly understood from the followingdescription of some embodiments thereof, given by way of example only,with reference to the accompanying drawings, in which:—

FIG. 1 is a perspective view of an embolic protection system pack;

FIG. 2 is a plan view of a delivery catheter of the embolic protectionsystem;

FIG. 3 is a side, partially cross-sectional view of the deliverycatheter of FIG. 2;

FIG. 4 is an enlarged view of part of the delivery catheter of FIG. 3;

FIG. 4A is a perspective, partially cut-away view of the deliverycatheter;

FIG. 5 is a side, partially cross-sectional view of a handle piece ofthe delivery catheter of FIG. 3;

FIG. 6 is an enlarged view of part of the handle piece of FIG. 5;

FIG. 7 is an enlarged view of another part of the handle piece of FIG.5;

FIG. 8 is a perspective view of a female luer of the delivery catheterof FIG. 3;

FIG. 9 is a plan view of an inner catheter of the embolic protectionsystem;

FIG. 10 is a side, partially cross-sectional view of the inner catheterof FIG. 9;

FIG. 11 is an enlarged view of part of the inner catheter of FIG. 10;

FIG. 12 is an enlarged view of another part of the inner catheter ofFIG. 10;

FIG. 12A is a perspective, partially cut-away view of the innercatheter;

FIG. 13 is a plan view of the inner catheter and the delivery catheterassembled;

FIG. 14 is a side, partially cross-sectional view of the catheterassembly of FIG. 13;

FIG. 15 is an enlarged view of part of the catheter assembly of FIG. 14;

FIG. 16 is an enlarged view of another part of the catheter assembly ofFIG. 14;

FIG. 17 is a side view of the catheter assembly of FIG. 14 with theinner catheter in a distal configuration of use;

FIG. 18 is a side, partially cross-sectional view of an embolicprotection device of the embolic protection system;

FIG. 19 is a plan view of the embolic protection device of FIG. 18;

FIG. 20 is a side view of a pushing device of the embolic protectionsystem;

FIG. 21 is a side, cross-sectional view of a part of the pushing deviceof FIG. 8;

FIG. 22 is a side, partially cross-sectional view of a loading device ofthe embolic protection system;

FIG. 23 is an enlarged view of the detail of the loading device of FIG.22;

FIG. 23A is a cross sectional view of an alternative loading device;

FIGS. 24 to 27 are schematic views illustrating release and flushing ofthe catheter assembly of FIGS. 13 to 17;

FIGS. 28 and 29 are schematic views illustrating release of the pushingdevice of FIGS. 20 and 21;

FIG. 29A is a cross sectional view on the line AA in FIG. 29;

FIGS. 30 to 32(b) are schematic views illustrating loading of theembolic protection device of FIGS. 18 and 19 into the catheter assemblyof FIGS. 13 to 17;

FIGS. 33 and 34 are schematic views illustrating disassociation of theloaded catheter assembly of FIG. 32(a) from the loading device of FIGS.22 and 23;

FIG. 35 is a side view of a guidewire of the embolic protection system;

FIGS. 36 to 41 are schematic views illustrating delivery and deploymentof the embolic protection device of FIGS. 18 and 19 in a vasculature;

FIGS. 42 and 43 are schematic views illustrating treatment of thevasculature;

FIGS. 44 to 47 are schematic views illustrating retrieval of the embolicprotection device of FIGS. 18 and 19 from the vasculature;

FIGS. 48 to 56 are side, partially cross-sectional views of otherembolic protection devices of the embolic protection system;

FIGS. 57 and 58 are schematic views illustrating loading of embolicprotection devices into the catheter assembly of FIGS. 13 to 17;

FIGS. 59 to 61 are schematic views illustrating loading of the embolicprotection device of FIGS. 18 and 19 into the catheter assembly of FIGS.13 to 17 using a removable pulling device;

FIG. 62 is a side view of the loaded catheter assembly;

FIGS. 63 and 64 are schematic views illustrating loading of embolicprotection devices into the catheter assembly of FIGS. 13 to 17 usingthe pulling device of FIGS. 59 to 61;

FIGS. 65 to 69 are schematic views illustrating retrieval of an embolicprotection device from a vasculature;

FIG. 70 is a side view of another guidewire of the embolic protectionsystem;

FIGS. 71 to 74 are schematic views illustrating deployment of an embolicprotection device in a vasculature;

FIGS. 75 and 76 are schematic views illustrating deployment of anotherembolic protection device in the vasculature using tethers;

FIG. 77 is a schematic view illustrating release of a tether of FIGS. 75and 76;

FIGS. 78 to 81 are schematic views illustrating delivery and deploymentof an embolic protection device of a rapid exchange embolic protectionsystem in a vasculature;

FIG. 82 is a side, partially cross sectional view of another embolicprotection system;

FIG. 83 is a side, partially cross sectional view of a further embolicprotection device; and

FIGS. 84 and 85 are cross sectional views of a distal portion ofcatheters.

DETAILED DESCRIPTION

Referring to the drawings there is illustrated a transvascular embolicprotection system according to the invention for safely capturing andretaining embolic material released during an interventional procedurewhile maintaining blood flow.

The embolic protection system comprises an embolic protection device 1,a delivery catheter 2 for delivery of the embolic protection device 1 toa desired location in the vascular system and a proximal stop fordeployment of the embolic protection device 1. The device 1 iscollapsible from an expanded deployed configuration to a retracteddelivery configuration. The delivery catheter 2 has a pod 13 at thedistal end to define a reception space for the embolic protection device1 in the collapsed delivery configuration. The proximal stop in thiscase is provided by the distal end 27 of an inner catheter 25 whichextends towards the pod 13 of the delivery catheter 2 for deployment ofthe embolic protection device 1 from the pod 13.

In use, the embolic protection device 1 is loaded into the pod 13 of thedelivery catheter 2 which is delivered over a pre-positioned guidewire99. At a desired location the inner catheter 25 is moved relative to thedelivery catheter 2 to deploy the embolic protection device 1 from thepod 13. The delivery and inner catheters 2, 25 are then withdrawnleaving a bare guidewire 99 over which various devices such as adilation balloon and/or a stent can be advanced to the treatment site.Embolic material dislodged during the treatment procedure(s) iscollected in the embolic protection device 1. After treatment, thedevice 1 may be retrieved into a retrieval catheter 3. The guidewire 99may be left in place for further catheter advancements or may bewithdrawn with or subsequent to the withdrawal of the retrieval catheter3.

Referring in particular to FIG. 1 a pack 4 is provided to safely storeand prepare the embolic protection system for use. The pack 4 comprisesa vacuum-formed tray 5, typically of PETG. The tray 5 has a channel 6extending in a looped configuration around the tray 5 for receiving thedelivery catheter 2. The delivery catheter 2 has a proximal end 11 and adistal end 12. A handle 14 is provided at the proximal end 11, and theinner catheter 25 which extends through the delivery catheter 2 has aluer 36 at the proximal end. The luer 36 is located in the tray 5adjacent to the handle 14. The pod 13 is provided at the distal end 12of the inner catheter 2. A loading device 7 in the form of a funnelpiece is mounted in the tray adjacent to and, in this case extendinginto the pod 13. The embolic protection device 1 is mounted in itsexpanded configuration in a well 90 in the tray 5 adjacent to andextending into the loading device 7. A pushing device 8 for loading thecollapsible embolic protection device 1 is mounted in the tray 5adjacent to the embolic protection device 1. A syringe 91 is alsomounted in a recess 92 of the tray 5. The syringe 91 is used to flushthe system and, after flushing, the pushing device 8 is used to push theembolic protection device 1 through the loading device 7 and into thepod 13 of the delivery catheter 2 in the collapsed configuration. Thedelivery catheter 2 is now ready for advancement over the guidewire 99.

Referring now to FIGS. 2 to 8, the delivery catheter 2 is illustrated inmore detail. The delivery catheter 2 comprises a tubular body 10,typically of polyimide, or nylon extending between a proximal end 11 anda distal end 12. At the distal end 12 of the tubular body 10 a pod 13 isprovided, the pod 13 having a smaller wall thickness and in this case alarger internal diameter, as illustrated in FIG. 4, to define areception space for receiving the embolic protection device in acollapsed configuration. The handl 14, illustrated in detail in FIGS. 5to 7, is attached to the proximal end 11 of the tubular body 10, with astrain relief member 15 extending from the handle 14 partially along thetubular body 10. The handle 14 defines a central lumen 16 extendingbetween a proximal opening 17 and a distal opening 18. A side portopening 19 is provided in the handle 14, the side port 19 being incommunication with the central lumen 16 (FIG. 3). A female luer 20, asillustrated in FIG. 8, is also provided, the luer 20 being fixedlymounted in the side port 19. A double-start thread is provided at thefree end of the luer 20 for threadable attachment of, for example, aflushing syringe 91 to the luer 20.

In this case the proximal stop is provided by an inner catheter 25. Asillustrated in FIGS. 9 to 12, the inner catheter 25 comprises a tubularbody extending between a proximal end 26 and a distal end 27. Thetubular body comprises an inner tubular stem 28 extending between theproximal end 26 and the distal end 27, and an outer tubular stem 29,typically of polyimide, extending from the proximal end 26 onlypartially along the inner stem 28, as illustrated in FIG. 10. The outerstem 29 terminates in a protruding O-ring shoulder 30. An annular collar31 is slidably mounted to the outer stem 29 proximally of the O-ringshoulder 30 (FIG. 12). The female winged luer piece 36 is attached tothe proximal end 26 of the stems 28, 29 by means of a flair connector32. The winged luer 36 defines a central lumen 33 extending between aproximal opening 34 and a distal opening 35.

As illustrated in FIGS. 13 to 17, the inner catheter 25 is configuredfor insertion through the proximal opening 17 of the handle 14 andadvancement through the handle 14 and the tubular body 10 until thecollar 31 engages the handle 14 (FIG. 15) in the region of the proximalopening 17. The collar 31 is fixedly attached within the proximalopening 17 of the handle 14.

The inner catheter 25 is slidable relative to the delivery catheter 2between a retracted position, as illustrated in FIG. 14, in which thedistal end 27 of the inner catheter 25 is proximal of the pod 13defining the reception space in the delivery catheter 2 (FIG. 16), andan extended position, in which the distal end 27 of the inner catheter25 extends distally of the pod 13 of the delivery catheter 2 (FIG. 17).

Movement of the inner catheter 25 proximally relative to the deliverycatheter 2 is limited by engagement of the O-ring shoulder 30 with thecollar 31 (FIGS. 14 and 15).

The pod 13 of the delivery catheter 2 and the inner stem 28 of the innercatheter 25 at least partially comprise a stiff core, for example of ametallic material, such as stainless steel, encased in a more pliablebody, for example of a plastics material such as polyimide. The corescomprise a mesh of longitudinally oriented strips of the stiff materialand circumferentially oriented strips of the stiff material.

Accurate delivery of a filter to its intended location (a non-diseasedvessel area) is a particularly important concern in tortuous anatomywhere there is a limited area of non-diseased vessel. The accuracy ofdeployment is related to the build up of potential stain energy indelivery catheter systems. This strain energy is primarily a combinationof strain energy produced in the outer and inner shaft during thedeployment action. The designs described below referring in particularto FIGS. 4A and 12A detail a novel solution to these problems.

During the deployment action the outer shaft or delivery catheter 2 issubjected to high levels of tensile strain. The design/construction ofthe outer shaft 2 is such that the amount of strain energy that can bestored within the outer shaft is minimised. Low flexural stiffness isalso desirable in catheter design to ensure good catheter flexibility,trackability and low insertion forces. These attributes are achieved byincorporating high tensile elements 21 within the wall construction ofthe outer shaft 2. These high tensile elements 2 can be high tensilelongitudinal steel wires as shown in the example below or they may beflexible high tensile wires or fibers, carbon fibers and or kevlarfibers.

These fibers/wires are contained within the wall 22 of the catheterwhich may be a polymeric material (detailed in FIG. 4A is a polyimidewall). These wires/fibers provide the outer shaft with high tensilemodulus (minimal stretch)which results in a shaft that can not storemuch strain energy. The inclusion of the above high tensile elements 21allows for a low profile outer shaft 2. This low wall thickness outercatheter shaft therefore also has low flexural stiffness, goodflexibility, trackability and subsequently low insertion force. Theinner surface 23 of the lumen of this shaft 2 is a low friction (PTFE)material to minimise the friction strain energy incurred during thedeployment action.

During the deployment action the inner catheter shaft 25 is subjected tohigh levels of compression strain. The design/construction of the innershaft 25 is such that the modulus of compression is high which reducesthe amount of strain energy that can be stored within the inner shaft25. This is achieved by incorporating elements 24 with high compressionmodulus. These elements are contained within a material matrix 24A thatfurther enhances the compression modulus of the inner shaft 25. Theinclusion of the above high compression elements allows for a lowprofile outer shaft. The low wall thickness inner shaft will thereforealso have low flexural stiffness, good flexibility and trackability. Theexample illustrated in FIG. 14A is a high compression modulus steel wirebraid 24 contained within a polymeric matrix 24A. The inner lumen of theshaft 25 is made of a low friction (PTFE) material layer 24B. The outersurface of the shaft 25 is also provided with a low friction (FEP)material layer 24C. The layers 24 B and 24C minimise the frictionalstrain energy incurred during delivery and deployment. Due to thecombination of the above inner and outer shaft 2,25 the amount of strainenergy that can be stored within the system during use is very low. Dueto the low strain energy build up within the system a precise,controlled, low force deployment is achieved even in difficult vesselpaths.

In this case, the embolic protection device 1 comprises a collapsiblefilter element 40 for delivery through a vascular system of a patientand deployment at a desired location in the vascular system. FIGS. 18and 19 illustrate the filter element 40 in detail.

The filter element 40 comprises a collapsible filter body 41, acollapsible filter support frame 42 contacting the filter body 41, andan inner elongate sleeve 43 to which both the filter body 41 and theframe 42 are mounted. A proximal end 44 of the filter body 41 and aproximal end 45 of the frame 42 are both fixedly attached to a proximalend 46 of the sleeve 43, in this case by means of an adhesive bond. Adistal end 47 of the filter body 41 and a distal end 48 of the frame 42are free to slide over a distal end 49 of the sleeve 43.

The filter body 41 has a proximal inlet end and a distal outlet end. Theinlet end of the filter body 41 has one or more, in this case two, largeinlet openings 50, and the outlet end has a plurality of, in this caseapproximately three hundred, small outlet openings 51 sized to allowthrough passage of blood but to retain undesired embolic material withinthe filter body 41.

The filter support frame 42 is movable between a collapsed position formovement of the filter element 40 through a vascular system and anextended outwardly projecting position to support the filter body 41 inan expanded position. The frame 42 has a distal section 52, anintermediate section 53 for urging the filter body 41 in the expandedposition into apposition with a vascular vessel wall, and a proximalsection 54 extending proximally and radially inwardly of theintermediate section 53 (FIGS. 18 and 19).

At least part of the proximal section 54 of the frame is spaced distallyof the inlet openings 50 in the filter body 41 to accommodate inflow ofembolic material through the inlets 50 and into the expanded filter body41. The filter body 41 comprises one or more, in this case two, linkingwebs 55 between adjacent inlets 50, and a part of the proximal section54 of the frame extends radially inwardly in alignment with the webs 55,as illustrated in FIG. 19, to avoid occluding the inlets 50 to thefilter body 41 when the filter body 41 is in the expanded position. Inthis manner the possibility of embolic material becoming caught orhung-up on the proximal section 54 of the frame as the embolic materialflows distally through the inlet openings 50 is minimised.

The proximal section 54 of the frame comprises one or more frameelements, in this case four. At least one frame element, in this casetwo, provides the part of the proximal section 54 which is spaceddistally of the inlets 50, and at least one frame element, in this casetwo, provides the part of the proximal section 54 extending radiallyinwardly in alignment with the webs 55.

The proximal section of the frame runs generally parallel with a vesselwall and then turns radially inwards. The proximal arm(s) of the framehave a section that is displaced distally. The advantage of thisdisplacement is that it creates an inlet path which is offset andtherefore larger.

The frame elements are preferably of a shape memory material, such asNitinol, or of a superelastic material, and may have a plating of goldor other dense material around the Nitinol. The frame elementsfacilitate movement of the frame 42 between the collapsed position andthe extended outwardly projecting position. The frame 42 iselectropolished.

The sleeve 43 defines a lumen 56 extending therethrough for exchange ofthe filter element 40 over the guidewire 99. The distal end 49 of thesleeve 43 is engageable with a stop such as a stop on the guidewire 99.This is particularly useful for retrieval of the filter element 40 froma vascular system. The sleeve 43 is typically of polyimide.

The sleeve 43 acts as a barrier between the lumen 56 through which aguidewire may be exchanged, and the internal annular volume of thefilter body 41 within which embolic material is retained. In particular,the proximal end 46 of the sleeve 43 is proximal of the inlets 50, andthe distal end 49 of the sleeve 43 is distal of the small outlets 51.This ensures that all blood flows into the filter body 41 through theinlets 50, through the filter body 41 and out of the filter body 41through the small outlets 51 which are sized to retain undesired embolicmaterial within the filter body 41. The sleeve 43 prevents escape of anyembolic material from the filter body 41 into the lumen 56, for example,during exchange of medical devices over a guidewire received within thelumen 56, or during retrieval of the filter element 40.

A guide olive 57 is provided for atraumatic delivery of the filterelement 40 through a vascular system, the guide olive 57 forms anextension of the distal end 47 of the filter body 41 and taperingdistally inwardly for a smooth transition profile. In this case, theguide olive 57 is integral with the filter body 41 and is of thematerial Pellethane. As illustrated in FIGS. 18 and 19, the guide olive57 extends distally of the distal end 49 of the sleeve 43.

In use, the region of a vasculature in which the filter element 40 isdeployed is substantially straight for a length at least equal to thelongitudinal length of the filter element 40 to ensure apposition of thefilter body 41 with the vasculature wall. By directly mounting the guideolive 57 at the distal end 47 of the filter body 41, the overalllongitudinal length of the filter element 40 is reduced to define alongitudinally compact filter element 40. Thus, the user has greaterfreedom when choosing a site in a vasculature to deploy the filterelement 40 because the length of the vasculature which is required to bestraight is correspondingly reduced.

As illustrated in FIGS. 18 and 19, the distal end 48 of the frame 42acts to reinforce the proximal section of the guide olive 57 andprevents flaring of the sleeve 43. The guide olive 57 has a soft distaltip 58.

Two gold marker bands 59, 60 are provided mounted to the sleeve 43. Onemarker band 59 is fixedly attached to the olive 51 and one marker band60 is fixedly attached to the proximal end 45 of the frame 42. Themarker bands 59, 60 assist in visualisation of the filter element 40during an interventional procedure.

A transition element 61 is fixedly mounted to the proximal end 46 of thesleeve 43, in this case by means of an adhesive bond. The transitionelement 61 is sized to fit made the lumen of the delivery catheter 2 toprovide a smooth stiffness transition and prevent kinking.

Referring now to FIGS. 20 and 21, the pushing device 8 for loading thecollapsible filter element 40 into the pod 13 of the delivery catheter 2is illustrated. The pushing device 8 comprises a handle 70 for grippingthe pushing device 8 and an elongate stem in this case provided by awire 71, extending from the handle 70 for threading through the lumen 56of the filter element 40. The wire 71 defines a distal stop 72 forreleasably engaging with the distal end 49 of the sleeve 43 of thefilter element 40 to push the filter element 40 into the pod 13 of thedelivery catheter 2.

As illustrated in FIG. 21 the distal stop 72 is provided by an end 74 ofan outer hypotube 73 which extends from the handle 70 partially alongthe wire 71. The free end 74 of the hypotube 73 forms a step from thesmall diameter wire 71 proximal of the step to the larger diameterhypotube 73 distal of the step. The small diameter is preferablyapproximately 0.014″ (0.3556 mm), and the large diameter is preferablyapproximately 0.018″ (0.4572 mm). The hypotube 73 may be attached to thewire 71 by any suitable means, such as an adhesive means, or amechanical keying means, or by brazing, or soldering, or welding, or byany other suitable means.

The wire 71 may have a low friction coating, for example ofpolytetrafluoroethylene, for ease of threading of the wire 71 throughthe filter element 40. The handle 70 facilitates ease of gripping and ofuse of the pushing device 8.

It will be appreciated that the distal stop 72 may be provided integralwith the wire 71, for example by machining a step in the wire 71.

It will further be appreciated that the large diameter portion distal ofthe step may be only a locally defined feature on the wire 71 that doesnot extend distally to the handle 70.

The loading device 7 is illustrated in detail in FIGS. 22 and 23. Theloading device 7 defines a funnel having an inlet end 80 and an outletend 81, the inlet end 80 defining a larger cross-sectional area than theoutlet end 81, and the outlet end 81 being configured for co-operativealignment with the reception space of the delivery catheter 2.

The loading device 7 has means for radially compressing the filterelement 40 from the extended outwardly projecting position to thecollapsed position. In this case, the loading device 7 comprises a mainsupport 82 having a funnel-shaped bore formed from a frusto-conicalfilter element receiving portion terminating in a cylindrical portionformed by a thin walled loading tube 83 projecting from the main support82 for positioning within the reception space of the delivery catheter2.

The cone angle of the bore is chosen from an angle in the range ofbetween 15° and 65°, preferably between 35° and 45°.

The loading tube 83 is preferably formed from polyethyleneterephthalate(PET), and is mounted on a metal spigot 84, typically a grit blastedhypotube, by a combination of a polyolefin shrink tube bond and anadhesive bond. The metal spigot 84 is adhesively fixed to the mainsupport 82 which is formed from “Perspex” or a similar material. Theloading tube 83 may be coated with a lubricant.

Referring to FIG. 23A there is illustrated an alternative loading device85 in which an outer support 86 is provided around the pod 13 of thedelivery catheter 2. A smooth transition is provided by a funnel section87 and the distal end of the pod 13. The area between the outer support86 and the pod 13 may be a wetted annular space for ease of mounting anddemounting.

Referring to FIGS. 1 and 24 to 29, the tray 5 will now be described inmore detail. The tray includes integral projections 9 that extend intovarious recesses. The projections 9 releasably support the loadingdevice 7 in co-operative alignment with the delivery catheter 2 beforeloading and during the loading procedure. In particular, the loadingdevice 7 is supported with the loading tube 83 extending proximally intothe reception space of the delivery catheter 2 before loading and duringthe loading procedure. In addition, the projections 9 on the channelwall are configured to releasably support the pushing device 8 in aposition in which the distal stop 72 does not engage the filter element40 before the loading procedure commences.

The projections 9 are also configured to releasably support the luer 20of the delivery catheter 2 in the horizontal position illustrated inFIGS. 1 and 24. In this position it is not possible to slide thedelivery catheter 2 proximally in the channel 6, or, in theconfiguration illustrated, to flush the delivery catheter 2 through theluer 20.

A liquid retaining bath 90 is provided by recesses in the tray 5, thebath 90 having a depth sufficient to accommodate in a totally submergedstate the reception space of the delivery catheter 2 and the filterelement 40 for submerged loading of the filter element 40 through theloading device 7 and into the pod 13 of the delivery catheter 2. Asillustrated in FIG. 1, the channel 6 communicates with the bath 90, anda ramp is provided at an end of the channel 6 communicating with thebath 90 to direct the reception space downwards towards the bottom ofthe bath 90 but supporting the pod 13 of the delivery catheter 2 abovethe bottom of the bath 90 by means of a step.

The syringe 91 is provided for flushing the delivery catheter 2, theinner catheter 25, the loading device 7 and the filter element 40. Therecess 92 is provided in the tray 5 for snap retention of the syringe 91before use.

The components of the embolic protection system are placed in the pack 4in the following manner. The loading device 7 is snapped into place inthe channel 6, with the projections 9 releasably supporting the loadingdevice 7 in the position illustrated in FIG. 1.

The inner catheter 25 is inserted through the proximal opening 17 of thehandle 14, and advanced through the handle 14 and the tubular body 10until the collar 31 engages the proximal opening 17 of the handle 14.The collar 31 is fixedly attached within the proximal opening 17 of thehandle 14 by pushing the collar 31 home to create an interference fitbetween the collar 31 and the proximal opening walls. This catheterassembly is then looped through the channel 6 and held in place so thatthe loading tube 83 of the loading device 7 extends proximally into thepod 13 of the delivery catheter 2.

The wire 71 of the pushing device 8 is then threaded through the filterelement 40, a proximal end of the wire 71 is inserted through theloading device 7 and extended partially through the inner catheter 25.The handle 70 is snapped into place in the channel 6 by the projections9. In this configuration the filter element 40 is slidable over the wire71 but is normally positioned within the bath 90, as illustrated inFIG. 1. The projections 9 retain the pushing device 8 in a position inwhich the distal stop 72 is spaced distally of the bath 90, and so thedistal stop 72 does not engage the filter element 40 in this storageconfiguration, as illustrated in FIG. 1.

The syringe 91 is snapped into place in the recess 92, and the assembledpack 4 is now ready to be sealed and stored until required for use.

In this storage configuration the filter element 40 is in the expandedconfiguration. This is an advantageous arrangement. If the filterelement 40 was loaded into the delivery catheter 2 and stored in thecollapsed position for a long period of time, the filter element 40would be subject to material deformation, in particular to materialcreep. The assembled pack 4 of the invention may be safely stored forlong periods in a packaged configuration without risk of filter elementmaterial deformation. The pack 4 is placed in a porch and sealed.

When the assembled pack 4 is required for use, the seal is broken, thepack 4 is removed and the syringe 91 is removed from the recess 92. Theluer 20 of the delivery catheter 2 is rotated through 90° in a“bolt-action” to release the luer 20 from the snap-fit retainingprojections 9 in the tray 5, as illustrated in FIGS. 24 and 25. Thedelivery catheter 2 is now slidable proximally in the channel 6, and theluer 20 is now accessible for flushing (FIG. 25). The syringe 91 is usedto flush the delivery catheter 2 through the luer 20 (FIG. 26) and toflush the inner catheter 25 through the proximal opening 34 in thefemale luer piece 36 of the inner catheter 25 (FIG. 27). A salinesolution is generally used for flushing the catheters 2, 25. The syringe91 is also used to fill the bath 90 with saline solution, therebyimmersing the filter element 40, the reception space of the deliverycatheter 2 and the loading device 7 in the saline solution. This ensuresall removed from the system.

This flushing step is performed shortly before intended use. The filterelement 40 is completely visible and accessible to the user duringprepping. In this way, the user can squeeze or pinch parts of the filterelement 40 to ensure the filter element 40 is completely flushed of air.This is difficult if the filter element 40 was loaded into the deliverycatheter 2 upon assembly and stored for a potentially long period in thecollapsed position.

The flushed filter element 40 is now ready for loading into the pod 13of the delivery catheter 2. The pushing device 8 is rotated through 90°in a “bolt-action” to release the handle 70 from the snap-fit retainingprojections 9 in the tray 5, as illustrated in FIGS. 28 and 29. In thisconfiguration the pushing device is still retained to the tray (FIG.29A). The pushing device 8 is now free to slide proximally in thechannel 6 (FIG. 30), until the distal stop 72 engages with the distalend 49 of the sleeve 43 of the filter element 40 (FIGS. 31(a) and31(b)). Continued pushing of the pushing device 8 will push the filterelement 40 proximally towards the loading device 7 (FIG. 31(a)), throughthe loading device 7, thereby collapsing the filter element 40 from theextended outwardly projecting position of FIG. 31(a) to the collapsedposition of FIG. 32(a), and into the pod 13 of the delivery catheter 2(FIG. 32(a)) until the filter element 40 abuts the distal end 27 of theinner stem 28 of the inner catheter 25. Further pushing of the pushingdevice 8 moves the collapsed filter element 40 and the inner catheter 25proximally until the O-ring shoulder 30 of the inner catheter 25 abutsthe annular collar 31 fixed in the proximal opening 17 of the handle 14,as illustrated in FIGS. 14 and 15. An O-ring 39 is also provided betweenthe shoulder 30 and the collar 31.

The loading device 7 has thus far remained in co-operative alignmentwith the delivery catheter 2. Because the luer 20 of the deliverycatheter 2 has been released from the snap-fit retaining projections 9in the tray 5, as illustrated in FIG. 32(b), the catheter assembly isfree to slide proximally in the channel 6 away from the loading device7. When the pushing device 8 is further pushed proximally, this causesthe inner catheter 25 to move proximally and with it the deliverycatheter 2 due to the engagement of the O-ring shoulder 30 with thehandle 14. In this manner, the delivery catheter 2, the inner catheter25 and the collapsed filter element 40 are all moved together proximallyaway from the loading device 7, and thereby the loaded catheter assemblyis disassociated from the loading device 7 (FIG. 33).

The loaded catheter assembly is then removed from the channel 6 leavingthe loading device 7 and the pushing device 8 behind in the channel 6.The assembly of the loaded delivery catheter 2 and the inner catheter25, as illustrated in FIG. 34, is now ready for insertion into avascular system of a patient.

The filter element 40 is loaded into the pod 13 of the delivery catheter2 by a simple, single-direction pushing action. This minimises potentialloading difficulties.

The components of the pack 4 are retained in the correct loadingalignments by the tray 5. The pushing device 8 is completely separatedfrom the loaded catheter assembly after completion of the loadingprocedure.

In addition, the loaded filter element 40 is not attached or associatedin any way with the pushing device 8. Thus, the user is free to chooseany suitable guidewire, as desired, for subsequent delivery of thefilter element 40 through a vascular system of a patient.

Referring now to FIG. 35 the guidewire 99 of the embolic protectionsystem is illustrated in detail. The guidewire 99 is suitable for theexchange of the filter element 40 through a vascular system of a patientover the guidewire 99. The guidewire 99 defines a distal end 100 andcomprises a distal stop 101 to prevent relative movement of the filterelement 40 distally of the distal end 100 of the guidewire 99. Theportion of the guidewire 99 proximally of the distal stop 101 is barefor exchange of the filter element 40 and/or other medical devices overthe guidewire 99.

In this case the distal stop 101 is provided by a wire coil 102 fixedlyattached around the distal end 100 of the guidewire 99 (FIG. 35). Thecoil 102 has a larger outer diameter than the bare portion of theguidewire 99 to define a step from the small diameter bare portion ofthe guidewire 99 to the large diameter coil portion of the guidewire 99.The small diameter is preferably approximately 0.014″ (0.3556 mm), andthe large diameter is preferably 0.018″ (0.4572 mm). A curve istypically formed towards the distal end 100 of the guidewire 99 tofacilitate navigating and/or positioning the guidewire 99 in avasculature.

The coil 102 may be attached to the small diameter portion of theguidewire 99 by an adhesive means, or by a mechanical keying means, orby brazing, or soldering, or welding, or by any other suitable means ofattachment.

In this case, the guidewire 99 is partially of stainless steel, andpartially of a radiopoque material to aid the user in positioning theguidewire 99 accurately in a vasculature. The guidewire 99 has a coatingof a low friction material, for example of a fluoropolymer such aspolytetrafluoroethylene, or of a silicone material, or of a hydrophilicmaterial, for ease of advancement of the guidewire 99 through avasculature and ease of exchange of the filter element 40 and/or othermedical devices over the guidewire 99.

As illustrated in FIG. 35, the large diameter coil 102 extends distallyof the step to the distal end 100 of the guidewire 99. However it willbe appreciated that the large diameter portion of the guidewire 99 mayextend distally of the step only a part of the distance to the distalend 101 of the guidewire 99. The large diameter portion may taperdistally inwardly back to the small diameter in an arrow-head type shapeor by gradually tapering.

Referring now to FIGS. 36 to 41, delivery and deployment of the filterelement 40 at a desired location within a vasculature 110 isillustrated. The guidewire 99 will be selected to suit the geometry ofthe vasculature 110 to be negotiated, and/or the disease site, and/orthe preference of the user. The guidewire 99 is firstly inserted on itsown into the vasculature system of a patient and advanced through thevasculature 110 until the distal stop 101 of the guidewire 99 is distalof a treatment site such as a region of stenosis 111 in the vasculature110 (FIG. 36).

The curved distal end 100 of the guidewire 99 is often anchored in abend in the vasculature 110 distally of the stenosed region 111 (FIG.41) to facilitate some straightening of the anatomy by the user prior todelivery of the filter element 40.

The loaded delivery catheter assembly of FIG. 34 is then inserted intothe vasculature system and advanced over the guidewire 99 through thevasculature 110, until the pod 13 of the delivery catheter 2 with thecollapsed filter element 40 therein is positioned at a desired locationof the vasculature 110 distally of the stenosed region 111 (FIG. 37). Atleast part of the filter element 40, in this case part of the distal end58 of the guide olive 57, protrudes distally out of the pod 13 of thedelivery catheter 2 during advancement of the delivery catheter 2through the vascular system to minimise trauma to the vessel walls. Theolive also provides a stiffness transition.

The delivery catheter 2 is retracted while maintaining the position ofthe inner catheter 25 (FIG. 38). In this way the distal end 27 of theinner stem 28 of the inner catheter 25 acts as a proximal stop againstwhich the transition element 61 of the filter element 40 abuts, thus thedistal end 27 of the inner stem 28 of the inner catheter 25 preventsretraction of the collapsed filter element 40 with the delivery catheter2. As the restraining delivery catheter 2 is withdrawn, the filterelement 40 is freed to expand from the collapsed, delivery configurationto the extended, outwardly projecting position of FIG. 39.

The filter element 40 may alternatively be deployed by advancing theinner catheter 25 while maintaining the position of the deliverycatheter 2. In this case the distal end 27 of the inner stem 28 of theinner catheter 25 effectively acts as a pusher to eject the collapsedfilter element 40 from the pod 13 of the delivery catheter 2, andthereby facilitate expansion of the filter element 40 to the deployedconfiguration of FIG. 39.

It will be appreciated that the filter element 40 may be deployed by anysufficient movement of the delivery catheter 2 proximally relative tothe inner catheter 25, thereby engaging the distal end 27 of the innerstem 28 of the inner catheter 25 with the filter element 40 tofacilitate deployment of the filter element 40.

The construction of the pod 13 of the delivery catheter 2 and the innerstem 28 of the inner catheter 25 prevent deformation of the pod 13 andthe inner stem 28 during deployment of the filter element 40. Inparticular, elongation of the pod 13 and compression of the inner stem28 are avoided. This ensures that the filter element 40 is accuratelyand smoothly deployed in the desired location in the vasculature 110.

In the extended outwardly projecting position the filter body 41 is incomplete circumferential apposition with the wall of the vasculature 110over a length substantially equal to the intermediate section 53 of thefilter support frame 42.

After deployment of the filter element 40 both the delivery catheter 2and the inner catheter 25 are retracted and withdrawn from thevasculature 110, leaving the guidewire 1 in place in the vasculature110, and the deployed filter element 40 in place in the vasculature 110distally of the stenosed region 111 (FIGS. 40 and 41).

The guidewire 99 is not attached to the filter element 40, and thus theguidewire 99 is free to rotate and/or to move longitudinally relative tothe deployed filter element 40. This is highly advantageous as itprevents any accidental movement of the guidewire 99 causing twistingand/or dislodging of the deployed filter element 40. Thus, the user hasmore freedom to carry out a treatment procedure on the stenosed region111 without the risk of intimal abrasion, or of the deployed filterelement 40 becoming dislodged or in some other way creating a potentialflow path for embolic material around the filter element 40.

In addition, the portion of the guidewire 99 in place in the vasculature110 proximal of the deployed filter element 40 is bare. This bareportion of the guidewire 99 facilitates the exchange of a wide varietyof different medical devices, for example a treatment means, over thebare guidewire 99 while the deployed filter element 40 remains in placein the vasculature 110. Examples of such medical devices are atherectomydevices to carry out an atherectomy procedure on the stenosed region111, or an angioplasty balloon 112 to carry out an angioplasty procedureon the stenosed region 111, as illustrated in FIG. 42, or a stent 113 tocarry out a stenting procedure on the stenosed region 111, asillustrated in FIG. 43, or any possible combination of these procedures,or any other therapeutic or diagnostic procedure. Any embolic materialreleased during such an interventional procedure will be collected andsafely retained in the filter element 40.

After completion of an interventional procedure, for example a treatmentof the stenosed region 111, the retrieval catheter 3 is flushed, forexample with a saline solution, using the syringe 91. In this case, theretrieval catheter 3 comprises an elongate tubular centring catheter121. The centring catheter 121 has a tapered distal tip 122 whichprotrudes distally of a distal end 120 of the retrieval catheter 3during advancement through the vasculature 110, as illustrated in FIG.44, to prevent snagging of the retrieval catheter 3 on the stent 113,and to minimise vessel trauma.

The retrieval catheter 3 is inserted into the vascular system andadvanced over the bare guidewire 99 until the distal end 120 of theretrieval catheter 3 is distal of the stent 113 (FIG. 44). The retrievalcatheter 3 is then further advanced distally over the guidewire 99 whilemaintaining the position of the centring catheter 121 until the distalend 120 of the retrieval catheter 3 is immediately proximal of thedeployed filter element 40. The guidewire 99 is retracted to engage thedistal stop 101 with the distal end 49 of the sleeve 43 of the filterelement 40.

The distal stop 101 of the guidewire 99 may alternatively be engagedwith the distal end 49 of the sleeve 43 of the filter element 40 byadvancing the retrieval catheter 3 further distally to engage thedeployed filter element 40 and push the deployed filter element 40distally until the distal end 49 of the sleeve 43 of the filter element40 engages the distal stop 101 of the guidewire 99. In this case noretraction of the guidewire 99 is necessary to engage the distal stop101 with the distal end 49 of the sleeve 43 of the filter element 40.

It will be appreciated that any suitable combination of advancement ofthe retrieval catheter 3 and retraction of the guidewire 99 may beemployed to effect engagement of the distal stop 101 of the guidewire 99with the distal end 49 of the sleeve 43 of the filter element 40.

With the distal stop 101 of the guidewire 99 engaging the distal end 49of the sleeve 43 of the filter element 40, the retrieval catheter 3 isadvanced while maintaining the position of the guidewire 99 (FIG. 45).

This causes the filter element 40 to collapse into the retrievalcatheter 3 until the filter element 40 is retrieved into the retrievalcatheter 3 (FIG. 46).

The filter element 40 may alternatively be retrieved into the retrievalcatheter 3 by retracting the guidewire 99 while maintaining the positionof the retrieval catheter 3 to collapse and retrieve the filter element40 into the retrieval catheter 3. In this case the guidewire 99 acts topull the filter element 40 proximally into the retrieval catheter 3.

It will be appreciated that the filter element 40 may be retrieved byany suitable movement of the retrieval catheter 3 distally relative tothe guidewire 99.

The distal stop 101 facilitates retrieval of the filter element 40 bypreventing the filter element 40 moving distally of the distal end 100of the guidewire 99.

The guide olive 57 of the filter element 40 may or may not protrudedistally out of the distal end 120 of the retrieval catheter 3 aftercollapse of the filter element 40.

The retrieval filter element 40 is then withdrawn from the vasculature110 by withdrawing the retrieval catheter 3 and the centring catheter121 together from the vasculature 110.

The guidewire 99 may be left in place in the vasculature 110 after theretrieval catheter 3, the centring catheter 121, and the retrievalfilter element 40 have been withdrawn from the vasculature 110, asillustrated in FIG. 47. Alternatively the guidewire 1 may be withdrawnfrom the vasculature 110 upon withdrawal of the retrieval catheter 3,the centring catheter 121, and the retrieval filter element 40.

When the bare guidewire 99 is left in place in the vasculature 110 afterwithdrawal of the retrieval catheter 3, a further treatment ordiagnostic means may be advanced over the bare guidewire 99 to accessany desired location in the vasculature 110. The position of the bareguidewire 99 may be adjusted proximally or distally, as desired, to suita further treatment or diagnostic procedure. Otherwise a fluroscopicassessment of the treated vessel may be made through the guidingcatheter or sheath prior to withdrawal of the guidewire. This isdesirable.

The embolic protection system of the invention offers considerableclinical advantages. The arrangement allows a clinician to select asuitable guidewire from a range of such guidewires. This providesenhanced flexibility by ensuring that filter performance can beoptimised. The embolic protection device is not dedicated to aparticular guidewire.

Because the embolic protection device is not attached to the guidewire,the guidewire which is first advanced through a vasculature can have alow profile and be tailored to the proposed procedure or vasculature.Consequently, the guidewire can easily navigate narrow and tortuousregions of the vasculature.

Thus, a clinician may readily select a particular type of guidewirewhich provides the appropriate flexibility and performance required fora particular vascular procedure being performed. The system alsofacilitates the safe crossing of a lesion not only in a first lesion.

Another important advantage is that because the embolic protectiondevice is not attached to the guidewire, if the embolic protectiondevice is under-sized with respect to the region of the treatment siteit is free to be carried by blood flow to a distal narrowed section ofthe vasculature at which the embolic protection device effectivelyachieves apposition with the vessel wall. This ensures that all bloodflow with entrained embolic material passes through the embolicprotection device. The guidewire distal stop prevents movement of theembolic protection device distally off the guidewire.

The possibility of successfully achieving filter deployment at theintended site is significantly improved due to:

-   -   Initial crossing with a bare guidewire is easier as a bare        guidewire has an extremely low profile, is highly trackable and        highly pushable.    -   Attempted crossing with a bare guidewire presents a very low        risk of an embolic event due to its low profile, and atraumatic        tip.    -   Once the bare wire is across the lesion, crossing with the        filter delivery system is simplified. Advancing the tip of the        guidewire and positioning it in the distal vasculature provides        additional support to the filter delivery catheter.

The possibility of successfully delivering other catheters andinterventional devices to the lesion area is enhanced because of theindependent movement compatibility of the deployed filter and guidewire.The guidewire tip can be advanced into the distal vasculature to provideanchorage during the advancement of additional catheters and devices.The filter position is maintained by visual apposition and blood flowforces. In this configuration the wire provides extra support to thecatheter or interventional device being advanced. This increases thepossibility of delivering the catheter to the intended location andminimises the possibility of an uncontrolled proximal movement of theguidewire/filter. This uncontrolled proximal movement occurs when theguidewire has insufficient support to guide an advancing catheter,through a tortuous path.

With fixed wire systems the filter may be quickly withdrawn back intothe lesion area with increased risk of an embolic event or stentdislodgement. The design of this invention substantially eliminates someof these serious clinical risks.

Referring now to FIGS. 48 to 56 there is illustrated other embolicprotection devices which are similar to the embolic protection device ofFIGS. 1 to 47, and similar elements are assigned the same referencenumerals in FIGS. 48 to 56.

In the case of the embolic protection devices of FIGS. 48 to 51 thelumen 56 of the sleeve 43 is of a diameter greater than the outerdiameter of the pushing device distal stop 72, and greater than thediameter of the guidewire distal stop 101. Thus, the distal end 49 ofthe sleeve 43 is not engageable with either the distal stop 72 of thepushing device 8 or the distal stop 101 of the guidewire 99. Instead anengagement grip 130 is provided on an inner wall of the sleeve 43, theengagement grip 130 providing an abutment for engagement with the distalstop 72 of the pushing device 8, and for engagement with the distal stop101 of the guidewire 99.

The engagement grip 130 may be provided at the proximal end 46 of thesleeve 43 (FIGS. 48 and 50) or at the distal end 49 of the sleeve 43, orat any suitable point along the length of the sleeve 43 as desired(FIGS. 49 and 51).

The engagement grip 130 may be provided by a relatively short stoprigidly attached to the inner wall of the sleeve 43, as illustrated inFIGS. 48 and 49, for example by chemical means, such as an adhesive, orby mechanical means, such as welding, or brazing, or soldering, orkeying means.

Alternatively the engagement grip 130 may be provided by crimping aportion of the sleeve 43, as illustrated in FIGS. 50 and 51.

In the case of FIGS. 52 to 54, the distal end 49 of the sleeve 43 isengageable with the distal stop 72 of the pushing device 8, and thedistal stop 101 of the guidewire 99. However, the sleeve 43 does notextend along the length of the filter body 41 as far distally as in theembolic protection device of FIGS. 1 to 51. The sleeve 43 may terminateclose to the distal end 47 of the filter body 41 (FIG. 52), or close tothe proximal end 44 of the filter body 41 (FIG. 54), or at any suitablepoint along the filter body 41 (FIG. 53).

In the case of FIGS. 55 and 56, a distal portion of the lumen 56 of thesleeve 43 is of a diameter greater than the outer diameter of thepushing device distal stop 72, and greater than the diameter of theguidewire distal stop 101, and a proximal portion of the lumen 56 of thesleeve 43 is of a smaller diameter to facilitate engagement of thedistal stop 72 of the pushing device 8 and engagement of the distal stop101 of the guidewire 99 with a step 140 in the sleeve 43. The step 140may be provided by overlapping a small diameter sleeve with a largediameter sleeve (FIG. 55), or alternatively the step 140 may be providedintegral with the sleeve 43 for example by machining the step 140 intothe sleeve 43.

Referring to FIG. 57 there is illustrated the loading of an embolicprotection device, which is similar to that illustrated above in FIG.49, into the pod 13 at the distal end 12 of the delivery catheter 2. Theloading procedure is similar to that described above with reference, inparticular, to FIGS. 28 to 34. In the case of FIG. 57, the distal stop72 on the pushing device 8 engages the engagement grip 130 on the innerwall of the sleeve 43 to push the embolic protection device through theloading device 7 and into the delivery catheter reception space, therebycollapsing the embolic protection device, as described previously.

FIG. 58 illustrates the loading of an embolic protection device, whichis similar to that illustrated above in FIG. 48, into the pod 13 of thedelivery catheter 2.

It will be appreciated that the engagement grip 130 may be of anysuitable configuration that facilitates engagement with the distal stop72 of the pushing device 8 for loading the embolic protection deviceinto the pod 13 of the delivery catheter 2.

Referring to FIGS. 59 to 62 there is illustrated an alternative loadingof the filter element 40 into the pod 13 at the distal end 12 of thedelivery catheter 2, which is similar to the loading procedure describedabove with reference, in particular, to FIGS. 28 to 36. In this case, apulling device 150 is provided in place of the pushing device 8. Thepulling device 150 is similar to the pushing device 8 described above,in particular with reference to FIGS. 20 and 21. However, the wire 71 ofthe pulling device 150 extends proximally through the inner catheter 25,and out of the proximal opening 34 of the catheter for manipulation by auser.

The filter element 40 is loaded by pulling the pulling device 150proximally to engage the distal stop 72 of the pulling device 150 withthe distal end 49 of the sleeve 43. Further pulling of the pullingdevice 150 draws the filter element 40 through the loading device 7 andinto the pod 13 at the distal end 12 of the delivery catheter 2, therebycollapsing the filter element 40, in a manner similar to that describedpreviously. Further pulling of the pulling device 150 proximallydisassociates the loaded catheter assembly from the loading device 7(FIG. 62), as described previously.

Referring to FIG. 63 there is illustrated the loading of an embolicprotection device, which is similar to that illustrated above in FIG.49, into the pod 13 at the distal end 12 of the delivery catheter 2. Theloading procedure is similar to that described above in FIGS. 59 to 62.In the case of FIG. 63, the distal stop 72 of the pulling device 150engages the engagement grip 130 on the inner wall of the sleeve 43 topull the embolic protection device through the loading device 7 and intothe delivery catheter reception space, thereby collapsing the embolicprotection device.

FIG. 64 illustrates the loading of an embolic protection device, whichis similar to that illustrated above in FIG. 48, into the pod 13 of thedelivery catheter 2 using the pulling device 150.

Referring to FIGS. 65 to 69 there is illustrated the retrieval of anembolic protection device, which is similar to that described above inFIG. 48, into the retrieval catheter 3. The retrieval procedure issimilar to that described above with reference, in particular, to FIGS.44 to 47. In this case, the distal stop 101 on the guidewire 99 engagesthe engagement grip 130 on the inner wall of the sleeve 43 to preventthe embolic protection device moving distally relative to the distalstop 101 on the guidewire 1 during retrieval.

It will be appreciated that the engagement grip 130 may be of anysuitable configuration that facilitates engagement with the distal stop101 of the guidewire 99 for retrieving the deployed embolic protectiondevice into the retrieval catheter 3.

FIG. 70 illustrates another guidewire 160 of the embolic protectionsystem, which is similar to the guidewire 99 of FIGS. 1 to 69, andsimilar elements are assigned the same reference numerals in FIG. 70. Inthis case, the guidewire 160 does not comprise a step from a smalldiameter portion to a large diameter portion.

FIGS. 71 to 74 illustrate the deployment of an embolic protection deviceof the embolic protection system which has been delivered over theguidewire 160 of FIG. 70. The delivery and deployment procedure issimilar to that described above with reference, in particular to FIGS.36 to 41. In this case, however, a tapered ring 161 is provided slidablymounted on the guidewire 160 between the distal end 27 of the inner stem28 of the inner catheter 25 and a proximal end 163 of the embolicprotection device.

To deploy the embolic protection device at a desired location in thevasculature 110, the delivery catheter 2 is retracted while maintainingthe position of the inner catheter 25. The retraction of the deliverycatheter 2 initially draws the embolic protection device proximally dueto the frictional force acting between the pod 13 of the deliverycatheter 2 and the embolic protection device (FIG. 71). As the embolicprotection device is initially drawn proximally it abuts the taperedring and pushes the tapered ring 161 proximally until the tapered ring161 abuts the distal end 27 of the inner stem 28 of the inner catheter25 (FIG. 72). Further retraction of the delivery catheter 2 whilemaintaining the position of the inner catheter 25 causes the embolicprotection device and the tapered ring 161 to slide relative to oneanother along a tapered plane of contact 162. This movement exerts aninward force on the tapered ring 161 to lockingly engage the taperedring 161 to the guidewire 160. In this way the embolic protection deviceis taper-locked to the guidewire 160 by means of an interference fitbetween the embolic protection device and the tapered ring 161, and bymeans of an interference fit between the tapered ring 161 and theguidewire 160 (FIG. 73). The delivery catheter 2 and the inner catheter25 may then be withdrawn from the vasculature 110 to leave the deployedembolic protection device engaged to the bare guidewire 160 in place inthe vasculature 110 (FIG. 74).

The embolic protection device is retrieved in a manner similar to thatdescribed previously with reference to FIGS. 44 to 47. The retrievalcatheter 3 is advanced over the guidewire 160 until the retrievalcatheter 3 is proximally adjacent the deployed embolic protectiondevice. The retrieval catheter 3 is then further advanced whilemaintaining the position of the guidewire 160 to collapse and retrievethe embolic protection device into the retrieval catheter 3. Because theembolic protection device is taper-locked to the guidewire 160 it is notnecessary to provide a distal stop on the guidewire 160 for abutmentwith the embolic protection device. The taper-lock ensures no movementof the deployed embolic protection device distally relative to theguidewire 160 is possible, and thus facilitates retrieval of the embolicprotection device into the retrieval catheter 3. The retrieved embolicprotection device is then withdrawn from the vasculature 110 bywithdrawing the retrieval catheter 3 and the guidewire 160 together.

Referring to FIGS. 75 to 77 there is illustrated an embolic protectionsystem which is similar to the embolic protection system described abovewith reference to FIGS. 71 to 74, and similar elements are assigned thesame reference numerals in FIGS. 75 to 77. In this case the embolicprotection system comprises two tethers 170 with inwardly arcing hooks172 at distal ends of the tethers 170, the tethers 170 extending betweenthe inner catheter 25 and the delivery catheter 2. The embolicprotection device comprises co-operating recesses 171 in the proximalend 163 of the embolic protection device for receiving the tether hooks172, as illustrated in FIG. 76.

Deployment of the embolic protection device proceeds in a manner similarto that described above with reference to FIGS. 71 to 74. Duringretraction of the delivery catheter 2, the tethers 170 are alsoretracted to ensure that the embolic protection device is drawnproximally to effect a secure taper-lock of the embolic protectiondevice to the guidewire 160 (FIG. 76). The tethers 170 act in additionto the frictional force between the pod 13 of the delivery catheter 2and the embolic protection device to draw the embolic protection deviceproximally.

After deployment and taper-locking of the embolic protection device, thehooks 172 of the tethers 170 are unclipped by advancing the innercatheter 25 (FIGS. 76 and 77). The distal end 27 of the inner stem 28 ofthe inner catheter 25 engages the hooks 172 and levers the hooks 172outwardly disengaging the hooks 172 from the co-operating recesses 171(FIG. 77). The tethers 170 and the inner catheter 25 are then withdrawnfrom the vasculature 110 to leave the deployed embolic protection devicein place in the vasculature 110 taper-locked to the bare guidewire 160.

Referring to FIGS. 78 to 81 there is illustrated a rapid exchangeembolic protection system which is similar to the embolic protectionsystems of FIGS. 1 to 77, and similar elements are assigned the samereference numerals in FIGS. 78 to 81. In this case, the pod 13 of thedelivery catheter 2 comprises an elongate slit 180 and the inner stem 28of the inner catheter 25 comprises a rapid exchange aperture 181 forpassage of a guidewire 182 through the aperture 181 and the slit 180(FIG. 78).

The embolic protection device is delivered to a desired location in thevasculature 110 distally of the stenosed region 111 (FIG. 78) in amanner similar to that described previously with reference to FIGS. 36and 37. The embolic protection device is deployed by retracting thedelivery catheter 2 while maintaining the position of the inner catheter25 (FIGS. 79 to 81), which facilitates deployment of the embolicprotection device in a manner similar to that described previously withreference to FIGS. 38 and 39.

The slit 180 in the pod 13 of the delivery catheter 2 is aligned withthe rapid exchange aperture 181 in the stem 28 of the inner catheter 25to prevent occlusion of the rapid exchange aperture 181 during therelative movement of the delivery catheter 2 and the inner catheter 25.

The aperture 181 provided in a sidewall of inner stem 28 of innercatheter is preferably located at a position along the length of theinner catheter which is spaced a relatively longer distance from theproximal end of the catheter than from the distal end of the catheter.Additionally, delivery catheter 2 desirably incorporates an elongateslit 180 which is located adjacent the distal end the catheter andco-operates with aperture 181 and the guide wire 182 which exitstherethrough to facilitate a rapid exchange of the catheter and filterassembly over the guide wire, thereby promoting ease of exchange withoutthe necessity of utilising exchange wires or extension wires. Asillustrated in FIGS. 78-81, this arrangement permits use of rapidexchange wire techniques as well as controlled deployment and retrievalof the filter at the delivery pod portion 13 located at the distal endof delivery catheter 2.

This is advantageous in that it facilitates single operator use. Ashorter guidewire may be used than for conventional systems making thedevice less cumbersome.

Referring now to FIG. 82 there is illustrated another embolic protectionsystem 200 according to the invention. The system is similar to thesedescribed above and like parts are assigned the same reference numerals.In this case the guidewire 99 includes a proximal stop provided by astep 201 and the filter has a proximal engagement element provided byintegral projections 202 which extend radially inwardly. The projections202 are configured to pass over the proximal step 201 when the filterelement is being moved distally over the guidewire 99 for deployment butare prevented from moving proximally over the proximal step 201. Thus,the filter element, on deployment can move between the proximal anddistal stops on the guidewire. The arrangement may allow the filter tobe retrieved over the proximal step 202.

Referring to FIG. 83 there is illustrated a system 205 similar to thatof FIG. 82 and like parts are assigned the same reference numerals. Inthis case the proximal step on the guidewire is provided by a proximallytapering element 206.

The embolic protection device is not restricted to use with a particularguidewire because it is not attached or engaged with the guidewire inany way as it is advanced over the guidewire. This is a highlyadvantageous arrangement. If the guidewire proves unsuitable for somereason, for example because it is too large or not trackable enough toaccess a desired site in a vascular system, the guidewire may bereplaced with a more suitable guidewire, for example a guidewire withgreater flexibility. However, because the embolic protection device isindependent of the guidewire it may be used with any suitable guidewire.

The invention gives greater freedom to a user by providing a choice ofguidewires to suit a patient anatomy without requiring the user toselect the embolic protection device to be used with the guidewire untilafter successful crossing of a lesion with the guidewire.

Numerous vascular catheter functions are facilitated by the invention,such as:

(i) Permits Dye Injections:

After performing a therapeutic procedure (e.g. angioplasty oratherectomy), the embolic protection device can be retrieved if desired,in order to inject dye (over the remaining guidewire), such that minimalobstruction or interference occurs with the subsequent dye flowmeasurements. Alternatively, the wire can also be safelypartially-retracted “behind” or “upstream” of the treated area, prior toperforming the dye injection.

(ii) Delivery of Lytic Agents:

Depending upon therapeutic needs, lytic agents can be site-specificallydelivered to a region of interest, either with the embolic protectiondevice deployed, or with the embolic protection device retrieved, ifdesired.

(iii) Facilitates Stent Procedures:

Assuming appropriate design considerations have been incorporated, theretrieval sheath can also facilitate safe removal of the embolicprotection device following a stenting procedure. For example, afterdeployment of an intravascular stent, the process of removing theembolic protection device favours certain sheath designs, such as atapered distal tip. Specifically, the distal tip of the sheath needs topermit easy crossing of the stent in a manner which will not catch up or“snag” at the proximal edge of the implanted stent, nor along anyinwardly-projecting surface of the interior of the implanted stent, asthe sheath is being introduced. More specifically, the distal region ofthe retrieval sheath is also preferably formed of a material whichpermits radial expansion at the distal tip in order to accommodateretrieval of the embolic protection device.

(iv) Facilitates Guidewire Replacements:

Because this embolic protection system accommodates barewireintroduction, it is possible to replace a guidewire during a procedure,if desired. For example, during treatment of two or more, distallyspaced-apart lesions, it may become necessary to replace the initialguidewire during the procedure with another guidewire offering improvedsteering or distal flexibility. The present invention might support suchguidewire replacements as follows. First, the embolic protection deviceis retrieved into the retrieval sheath (which has already crossed thefirst lesion area). Then the wire can be withdrawn (or alternatively,the wire and embolic protection device together can be withdrawn), whilethe sheath remains across the lesion. Subsequently, a replacementguidewire can be introduced through the sheath lumen to the area ofinterest.

A number of engagement means between the embolic protection device andthe guidewire are described above which ensure that the embolicprotection device is anchored or tethered while the retrieval sheath isadvanced over the embolic protection device. It is also envisaged thatan engagement means may be provided between the embolic protectiondevice and the retrieval sheath after the filter is retrieved, to ensurethat there is a positive engagement between the embolic protectiondevice and the sheath. For example, frictional engagement means may beprovided on one or both of the embolic protection device and sheath. Forexample, projections, rings, or the like may be provided on the innersurface of the retrieval sheath adjacent the distal end thereof toprovide a frictional fit with the retrieved embolic protection device.Typical arrangements 210, 220 of this type are illustrated in FIGS. 84and 85. The frictional engagement may be provided by projections 225which may be of any type including continuous, discontinuous, radiallyand/or longitudinally extending.

The invention is not limited to the embodiments hereinbefore described,which may be varied in construction and detail.

1-67. (canceled)
 68. Apparatus for filtering emboli from blood flowingthrough a vessel, the apparatus comprising: a guide wire having proximaland distal regions, and proximal and distal stops on the distal region;and a filter element configured to rotate and translate on the guidewire between the proximal and distal stops, wherein the filter elementand the proximal stop are configured to permit advancement of the filterelement from the proximal region by passing in vivo over the proximalstop, the proximal stop thereafter prohibiting proximal retraction ofthe filter element over the proximal stop.
 69. The apparatus of claim 68wherein the distal stop limits translation of the filter element in adistal direction.
 70. The apparatus of claim 68 wherein the proximalstop has proximal and distal ends and a taper disposed therebetween. 71.The apparatus of claim 70 wherein the proximal end has a first diameterthat is less than a second diameter of the distal end.
 72. The apparatusof claim 70 wherein the filter element comprises a compliant memberconfigured to pass over the proximal stop.
 73. The apparatus of claim 68wherein the proximal stop and distal stop are spaced apart such adistance that the filter element, when deployed therebetween, will notbe disturbed by incidental longitudinal movements of the guide wire. 74.The apparatus of claim 68 wherein the proximal stop is configured toabut against a proximal portion of the filter element, after the filterelement is moved to the distal region, when the guide wire is advanced.75. The apparatus of claim 68 further comprising a plurality ofself-expanding struts coupled between a capture ring and a filter sac.76. The apparatus of claim 68 wherein the proximal stop comprises atleast one depressible tab having proximal and distal ends, wherein theproximal end is affixed to the guide wire.
 77. The apparatus of claim 76wherein the distal end of the depressible tab is biased radially outwardfrom the guide wire in a relaxed state.
 78. The apparatus of claim 77wherein the distal end of the depressible tab is configured to abutagainst the filter element once the filter element is moved to thedistal region.
 79. The apparatus of claim 77 wherein the depressible tabfurther comprises a contracted state in which the distal end issubstantially flush with an exterior surface of the guide wire.
 80. Theapparatus of claim 76 wherein the depressible tab is configured tofacilitate distal advancement of the filter element over the proximalstop in the contracted state.
 81. The apparatus of claim 68 wherein theproximal stop includes a bent section of the guide wire, the bentsection including a proximal taper and a distal taper.
 82. The apparatusof claim 81 wherein the proximal taper comprises a first angle withrespect to a longitudinal axis of the guide wire and the distal tapercomprises a second angle with respect to the longitudinal axis, whereinthe first angle is less than the second angle.
 83. A method forfiltering emboli from blood flowing through a vessel, the methodcomprising: providing apparatus comprising a guide wire having a distalregion including a distal stop, a proximal stop disposed proximal of thedistal stop, and a filter element disposed for-translation on the guidewire; transluminally inserting the guide wire into a vessel; distallyadvancing the filter element in a contracted state over the proximalstop; and deploying the filter element, distal of the proximal stop andproximal of the distal stop, to engage a wall of the vessel and filteremboli out of blood flowing through the vessel.
 84. The method of claim83 further comprising advancing a treatment device along the guide wireto treat a portion of the vessel proximal of the location of the filterelement, wherein incidental rotation or translation of the guide wirerelative to the filter element does not displace the filter element. 85.The method of claim 84 further comprising a step of, after use of thetreatment device is completed, pulling the guide wire proximally so thatthe distal stop engages the filter element and causes the filter elementto return to the contracted state.
 86. The method of claim 83 furthercomprising: distally advancing the guide wire; and causing the proximalstop to abut and urge the filter element distally.
 87. The method ofclaim 83 wherein providing apparatus comprising a proximal stopcomprises providing a taper on the guide wire, the method furthercomprising: distally advancing the filter element in the contractedstate over the taper; and causing a distal end of the taper to abut andreposition the filter element when the guide wire is advanced distallyby a physician.
 88. The method of claim 83 wherein providing apparatuscomprising a proximal stop comprises providing a bent section of theguide wire having proximal and distal tapers, the method furthercomprising: distally advancing the filter element in the contractedstate over the proximal and distal tapers; and causing the distal taperto abut and reposition the filter element when the guide wire isadvanced distally by a physician.
 89. The method of claim 83 whereinproviding apparatus comprising a proximal stop comprises providing atleast one depressible tab having a proximal end affixed to the guidewire and a distal end, the method further comprising: providing thedepressible tab in a relaxed state wherein the distal end is biasedradially outward from an exterior surface of the guide wire; distallyadvancing the filter element over the depressible tab to cause thedistal end of the depressible tab to be substantially flush with theexterior surface of the guide wire; and returning the depressible tab tothe relaxed state after the filter element is advanced distal of theproximal stop.
 90. A method for filtering emboli from blood flowingthrough a vessel, the method comprising: providing apparatus comprisinga guide wire having a distal region including a distal stop, a proximalstop disposed proximal of the distal stop, and a filter element disposedfor translation on the guide wire, the filter element and proximal stopbeing configured to prohibit proximal retraction of the filter elementover the proximal stop; transluminally inserting the guide wire into avessel; distally advancing the filter element in a contracted state overthe proximal stop; and deploying the filter element, distal of theproximal stop and proximal of the distal stop, to engage a wall of thevessel and filter emboli out of blood flowing through the vessel.